Structural changes in thermal stabilization of polyacrylonitrile fibre

The following conclusions were drawn from the experimental data examined: IR spectroscopy can be used to evaluate the molecular orientation of initial and oxidized PAN fibre and demonstrate its succession during processing; the deformation regimes of oxidation of PAN fibre affect the degree of preservation of its molecular orientation and the level of the properties of the carbon fibre obtained.Translated from Khimicheskie Volokna, No. 1, pp. 17–19, January–February, 1995.     

Oxidation of organosulfur compounds by hydrogen peroxide in the presence of niobium and vanadium peroxo complexes

New niobium(V) peroxo complexes containing aspargine and Schiff base ligands were synthesized, and their structures were solved by IR, NMR, and mass spectrometric methods. They were found to be catalytically active for the peroxidation of methyl phenyl sulfide and benzothiophene to the corresponding sulfoxide and sulfones. It was shown that vanadium(V) peroxo complexes with the same ligands are less active in the oxidation of methyl phenyl sulfide than the niobium complexes.     

Oxidative desulfurization of diesel fuels in the presence of crown ethers and transition metal peroxo complexes

The catalytic activity of crown ethers and their complexes with transition metal cations in diesel fuel desulfurization has been investigated. With dibenzo-18-crown-6 in combination with NbCl₅, the total sulfur content of the fuel can be reduced by a factor of 2 or larger. The effects of the reaction temperature, nature of metal and crown ether, and sorbent acidity on the residual sulfur content are reported. Methods of separation of oxidized compounds, namely adsorption chromatography and extraction are compared in terms of desulfurization efficiency. The latter method is demonstrated to be preferable.     

Oxidation of methylphenyl sulfide with hydrogen peroxide in the presence of crown ethers and their complexes with amino acids

The oxidation of methylphenyl sulfide, benzothiophene, and dibenzothiophene with hydrogen peroxide in the presence of crown ethers was studied. The major product of the oxidation was methylphenyl sulfoxide. The reaction was retarded by the addition of amino acids, which formed 1: 1 complexes with the crown ethers. The oxidation of the diesel fraction with hydrogen peroxide can decrease the sulfur content in it.     

DSResSol: A Sequence-Based Solubility Predictor Created with Dilated Squeeze Excitation Residual Networks

Protein solubility is an important thermodynamic parameter that is critical for the characterization of a protein’s function, and a key determinant for the production yield of a protein in both the research setting and within industrial (e.g., pharmaceutical) applications. Experimental approaches to predict protein solubility are costly, time-consuming, and frequently offer only low success rates. To reduce cost and expedite the development of therapeutic and industrially relevant proteins, a highly accurate computational tool for predicting protein solubility from protein sequence is sought. While a number of in silico prediction tools exist, they suffer from relatively low prediction accuracy, bias toward the soluble proteins, and limited applicability for various classes of proteins. In this study, we developed a novel deep learning sequence-based solubility predictor, DSResSol, that takes advantage of the integration of squeeze excitation residual networks with dilated convolutional neural networks and outperforms all existing protein solubility prediction models. This model captures the frequently occurring amino acid k-mers and their local and global interactions and highlights the importance of identifying long-range interaction information between amino acid k-mers to achieve improved accuracy, using only protein sequence as input. DSResSol outperforms all available sequence-based solubility predictors by at least 5% in terms of accuracy when evaluated by two different independent test sets. Compared to existing predictors, DSResSol not only reduces prediction bias for insoluble proteins but also predicts soluble proteins within the test sets with an accuracy that is at least 13% higher than existing models. We derive the key amino acids, dipeptides, and tripeptides contributing to protein solubility, identifying glutamic acid and serine as critical amino acids for protein solubility prediction. Overall, DSResSol can be used for the fast, reliable, and inexpensive prediction of a protein’s solubility to guide experimental design.     

Hydrogen peroxide oxidative desulfurization of model diesel fuel mixtures in the presence of crown ethers and transition metal peroxo complexes

The catalytic ability of crown ethers and their complexes with transition metal cations in the desulfurization reaction of mixtures that simulate diesel fuel has been investigated. It has been found that the use of monoaza-15-crown-5-ethers with an admixture of NbCl₅ resulted in a fourfold decrease of the total sulfur content, thereby indicating partial oxidation of benzothiophenes and dibenzothiophenes. The complexation of azacrown ethers with NbCl₅ has been studied by ¹H NMR spectroscopy. A moderate efficiency of adsorption purification procedure using silica and alumina for both initial and oxidized model mixtures has been revealed.     

Oxidative desulfurization of diesel fraction with hydrogen peroxide in the presence of catalysts based on transition metals

The oxidative desulfurization of a straight-run, nonhydrotreated diesel fraction (boiling range 178–342°C) containing benzothiophene, dibenzothiophene, their alkyl-substituted derivatives, and thioxanthene by the action of hydrogen peroxide in the presence of transition metal compounds (Na₂MoO₄, Na₂WO₄, NaVO₃, WO₃, tungstic acid, and heteropoly tungstate/molybdate H₃PMo₆W₆O₄0) in a biphasic system followed by the extraction of the oxidation products with dimethylformamide has been studied. The oxidation of the hydrocarbon fraction in the presence of heteropoly tungstate/molybdate under biphasic conditions provides for the removal of up to 82% of total sulfur.     

Structural features and strength of carbon fibres

Conclusions -- Dimensions, orientation of the ordered regions, and also the heterogeneous structure parameters have been determined for a number of foreign and domestic high-strength and high-modulus carbon fibres (CF). Characteristic features of the behavior of the heterogeneous structure of CF with change in dimensions of the ordered regions have been noted.-- It has been shown that small dimensions of the ordered and unordered regions are characteristic of high-strength CF together with an increased mean density of the unordered and porous phases.-- An attempt has been made to establish correlations between the ultimate strength of CF in extension and the heterogeneous structure parameters of the fibre.Translated from Khimicheskie Volokna, No. 1, pp. 47–49, January–February, 1991.     

Injuries of the heart and pericardium

The authors experience with surgical treatment of heart and pericardium injuries is summarized. A total of 38 patients were operated upon. The surgical aid consisted in simultaneous performance of the complex of reanimation measures, urgent thoracotomy and suturing of the heart wound. Thirty six patients have recovered, two died. One patient died due to mediastinitis, the other -- due to progressive cardiovascular insufficiency.